From the Director





by Rex Parker, Director

So Many Reasons to Keep Looking Up.  As the year 2017 winds down and the holiday spirit ascends, we can all share some satisfaction at an exciting event-filled year in our organization. I want to convey my deep appreciation for the efforts of our Officers, observatory Keyholders, and indeed all members of AAAP. This has been a year of progress on longer term goals, even as we enjoyed the opportunities right in front of us. Together we improved our observatory technology, provided remote astrophotography learning opportunities to members, had an amazing solar eclipse experience, shared several hands-on astro observing events, and experienced fascinating astronomy presentations. Attendance has been strong at Peyton Hall and membership is increasing. These are all hopeful signs of a vibrant organization looking upwards.

My destination this December is far away from Princeton, as my wife and I are travelling to the Orient for a few weeks of adventure. If all goes well I will see you at the January meeting in Peyton Hall. Meanwhile I hope you will turn out for the December 12 meeting as we have a great speaker program planned. Refer to the article by Program Chair Ira Polans in this issue.

Dark skies! — Rex

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From the Program Chair

By Ira Polans

The December AAAP meeting will be held on the 12th at 7:30PM in Peyton Hall on the Princeton University campus. The talk is by AAAP member William Murray on “The Life and Legacy of Charles Messier”.

Bill’s talk is an examination of the life of the famed 18th century French astronomer Charles Messier and a look at how his work 200 years ago affects amateur astronomers today. Charles Messier is best known today for his catalog of 110 “Messier objects”. The purpose of the catalog was to help astronomical observers, in particular comet hunters, distinguish between permanent and transient objects in the night sky. These objects turn out to be some of the best nighttime objects to introduce the public to.

We are still looking for volunteers to give a 10 minute talk at future club meeting. If interested, please contact me at Please let me know the topic and your availability.

There will not be a meet-the-speaker dinner prior to the club meeting.

We look forward to seeing you at the December meeting!

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November 14, 2017 Meeting Minutes

by Jim Poinsett, Secretary

  • After the presentation and the break Rex called the meeting to order.
  • Rex talked about light pollution and how LED lights blue shift and cause problems for viewing and astrophotography. He stressed the need to influence local authorities to use phosphor converted LEDs.
  • He also talked about how the spectra of light reflecting off the atmosphere of extra-solar planets is being analyzed for signs of life.
  • The subject of an interactive calendar for the website to sign up for outreach events was discussed. No current solution was known, additional research is needed.
  • How to make it clearer for visitors to our website to request an outreach event was brought up. Several suggestions were made .
  • The possibility of moving our website to a new hosting company was discussed. The possibility of getting increased space with our current hosting company is also a possibility. A report will be made at the next meeting.
  • As of the meeting date the observatory was not winterized and is fully operational.
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November 6, 2017 Board Meeting Minutes

by Jim Poinsett, Secretary

  • Minutes of the November 2017 Board Meeting of the AAAP
    • The meeting was called to order at 7:30
    • The first topic of the evening was about making the outreach chairperson and observatory chairperson positions members of the Board of Directors. The only negative brought up was the occasional difficulty of obtaining nominees for some of the board position. The main positive aspect was it would emphasize the importance of these positions. The board voted unanimously to put the amendment to a vote by the members. The members will be notified and the voting will take place after the first of the year.
    • Membership dues are now payable through PayPal.
    • The club policy on speaker expenses was brought up and it was decided that there does not exist a policy, expenses are handled on a case by case basis. It was decided to leave it that way.
    • It was decided to add a 10 minute presentation by a member at the beginning of each meeting. Volunteers are wanted and encouraged to speak up.
    • The SkyNet astrophotography program is continuing. Currently 23 members have signed up for accounts and 9 have used minutes.
    • Observatory topics were covered next
      1. There are several pieces of equipment at the observatory that are not being used, SBIG ST-10 CCD camera, Optec TCF autofocuser and an Optec IFW auto filter wheel. Since no one has used this equipment is several years the board has decided to sell it.
      2. The current Mallincam is a low resolution, NTSC analog camera. Possible replacements and costs will be presented at the next meeting.
      3. The need for gravel on the observatory driveway. A proposal will be prepared for the next meeting.
      4. There are some focusing issues on the Hastings and Mewlon scopes. The tapered end of the focuser on the Hastings is causing problems, it needs to be squared. Tom and John have offered to do the work to repair it.
      5. The possibility of the Mewlon needing collimation was discussed, the procedure has been found. The possibility of thermal issues causing focusing problems was discussed. Procedures to lessen the thermal issues will be tried before doing a collimation.
      6. The need to update and improve the alarm and security system at the observatory was discussed. Since we have internet access the board decided it would be appropriate to buy a system rather than pay a monthly fee to a monitoring service. Dave will put together a list of options.
    • A membership coordinator position was proposed. While the need to attract new and younger members was acknowledged it was decided not to create another position.
    • The board discussed buying an EAA telescope for outreach purposes. More research needs to be done before a decision will be made.
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Skynet exposed

by Ted Frimet

dare you seize the galaxy?

Hello Everyone,

I am new to Skynet and am trying to get started.  I have watched the videos but am confused on a couple things and would appreciate any advice.

For my first photo, I am trying to photograph M101.  Since these dimmer objects have a longer exposure time and use up credits quickly, I’d like to get this first shot right.  

Here are my questions:
1) Filters.  In the video, the lady drags in a separate screen from out of nowhere that gives more details about which filter is recommended for her demo shot on Saturn.  I can’t find this “recommendation” screen anywhere, so my questions are:  where is the screen located?  Do you have a recommendation on your own experience for a filter for galaxies (M101 magnitude 7.86) ?  

2) Exposure Time.  I see in the video that there is a recommended maximum exposure time. For M101 it is 120 with HiLum filter.  When you take your images, do you just choose the max time or will it be overexposed?

I see M101 can be photographed by a couple telescopes, but at a later time.  How do I select what time I want to request the telescope to take the image?  And when you set the time, is it our DST time or GMT or local time at the telescope?

Many thanks,


To answer your question on “which filter is recommended for her demo shot on Saturn”, click on the below link,


3. Observe Planets.

You will find the below table, which will list Saturn, its recommended filter, and exposure duration, as found in the above PDF.

Here is a copy of that table:

It isn’t too intuitive to find the “V” filter on Skynet. You are probably selecting telescopes, then filters which are supported by those telescopes.

I might suggest you reverse your selection process. That is, choose the filter first, and select from the list of telescopes then presented that offer those filter options.

Look for this graphic on Skynet:

As you can see, I have selected “Filters” after assigning my target. On the filters page, you will find the recommended “V” filter for Saturn. The selection looks just like this:

Where GenG (generic G’reen” is listed as “V”, greenish filter.
 Or you might try the Astrophotography Green filter.

Moving onto the second part, of your first question… Do you have a recommendation on your own experience for a filter for galaxies (M101 magnitude 7.86) ?

In the same referenced Skynet Lab, there is a table for recommended exposures and filters. The “open filter” setting is recommended for Spiral Galaxies.

Here is a shot of the Whirlpool galaxy at 30 seconds exposure, with Open filter setting:

We arrive at your second question.  I see in the video that there is a recommended maximum exposure time…When you have taken your images, do you just choose the max time or will it be overexposed?

The maximum time is presumed to keep the camera from overexposing. Having said that, go ahead and experiment. I haven’t tried past the maximum exposure time. You might find Skynet software presenting you with a warning, and a limitation on scope selection. See below:

I really enjoy your third and final question. It’s the best! How do I select what time I want to request the telescope to take the image?  And when you set the time, is it our DST time or GMT or local time at the telescope?

In the Skynet user interface, where you select your filters, and telescopes, you will find an advanced options. It will appear just below your AAAP time account information.

Select the check box titled “Delay the start of this observation until …UTC.” And fill in a time.

At first blush, and for a few entries, you may enter incorrect information. It happened to me.

If you are permitting Skynet to automatically choose the next available telescope, then it will, of course, make any adjustments to ephemeris data and time parameters for you.

Here is a referenced link on the web for EST to UTC conversion.

Rich, the 800 lb gorilla in the room is that when you are selecting a target, and it is in the “horizon” window then all is well.

A horizon graph, like the one below, may provide you with a good chance of getting an image:

However, if there is no target visibility (nothing above the 30 deg elevation marker – or a complete lack of “colored” lines – then cancel your request, and choose another target. This will most likely happen with planets. Alternatively, you could change the minimum visible hours from “1.0” to, say, 0.5 and try to squeak in an observation.

I hope that this has been of some help for you, and our readers, and enriches the experience with the Skynet Robotic Telescope Network.

Rex had a really good solid reply. It appears below:

Thanks Ted, those comments are really helpful in answer to Rich’s questions.  I’ll add a couple of other thoughts here.   

The CCD cameras in Skynet have anti-blooming sensors (e.g., KAF-16803), beneficial for imaging dim objects such as galaxies.  If a pixel registering a brighter area (e.g., galaxy core) becomes saturated (exceeds well depth capacity) it will not bloom vertical streaks the way non-anti-blooming CCD sensors do.  At longer exposures pixels corresponding to fainter regions of the object continue to increase in value as brighter pixels max-out (at the well depth value for the sensor), improving the overall image character by showing fainter regions with greater intensity.   

120 sec is a good starting point for galaxies.  Try “bracketing” a few exposures to see how this affects the image.  My SSRO group using PROMPT2 at Cerro Tololo uses 30 minute sub-frames for all deep sky work, and here at home in NJ I use 15 minute sub-frames.  However, as mentioned at the meeting, exposures of this length need active autoguiding to correct small tracking errors (otherwise even very small errors lead to trailing, out-of-round stars).  Skynet generally does not make auto-guiding available to the user due to complicating features, although it’s possible that at deeper levels in the user priority chain guiding may be possible.  

Luminance (L) filters are really IR cutoffs and are used mainly to attain parfocality with the other R,G, B filters.  Any filter in the light path causes a small but significant change in focal length, so not having a filter would cause problems.  Having to adjust focus for filter changes is inefficient.  Color imaging of deep sky objects is done by taking a series of L, R, G, and B filter frames and combining in software to make the color composite.  The luminance (L) filter has the greatest sensitivity (highest quantum efficiency) since the others filter out broader wavelengths.  It’s interesting to compare pixel brightness data for the same object at constant exposure times with L compared to R, G, and B filters.   

— Rex


I had inquired to Rich if we could use his follow-up, and publish results. Below, is our Amateur Astronomer’s first image taken from Skynet. It is M51 with its histogram adjusted in Afterglow software, ranging: min 40 max 99.2. The histogram feature, is a constraint on how much “white” and how much “black” will show thru in the final image.

Way to go, Rich! Awesome!!

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Voyagers on a Grand Tour

by Prasad Ganti

For forty years, they have been traveling towards the outer solar system and beyond. They are the twin space probes Voyager 1 and Voyager 2. Fueled by nuclear energy in the form of plutonium based thermal generators, Voyager 1 is the only man made object that cleared the boundary of our solar system and is in the interstellar region, the space between stars. Voyager 2 is fast approaching this milestone. They have gone further than any other man made object. Their engines and instruments are running for longer time than any other man made machine.

These space probes embarked on what is known as a Grand Tour. A tour of all the outer gaseous giants, namely Jupiter, Saturn, Uranus and Neptune. It is known as the Grand Tour because all these planets were aligned, an event which happens once in 175 years. It happened in the 1970s and was predicted by Gary Flandro of Jet Propulsion Laboratory earlier in 1964. When this alignment happens, a single space probe can visit each of these planets using the gravity assist of the earlier planet. When it reaches Jupiter, it uses the gravity assist of Jupiter to fling itself towards Saturn and so on. This way, all the four outer planets can be reached faster and with minimum amount of fuel.

The variable distances between the planets and the gravity assists are unique to space travel. We do not find such a concept on Earth. The distance between London and New York is always the same, as far as the human horizon of time can see. The distance between the planets varies because each is moving around the Sun at different speeds, and not in lockstep with each other. The Earth from where the space probes are launched, is itself a moving platform. So are the destination planets. The space probe gains the Earth’s momentum at the time of launch. When it reaches a destination planet, it can be a fly by or get captured by the planet’s gravity. If fly by, it can get a gravity assist like a slingshot, bends its path slightly, and hurl itself at a higher speed towards the next destination. Thus the planet’s momentum gets added to that of the space probe’s. It is like getting a push for free. This concept was amply demonstrated by the earlier probe Mariner 10 which visited Venus and Mercury in 1973-74.

NASA started planning for the twin space probes Voyager 1 and 2 to go on the Grand Tour. The initial plan was to visit Jupiter and Saturn only and later decide on Uranus and Neptune. Both the Voyagers were launched in 1977 within two weeks of each other. They reached Jupiter in 1979. Voyager 1 reached Saturn in 1980 and then went to its largest moon Titan. After that, it moved away from the planetary plane towards the interstellar space. It is important to note that the planets all move around the Sun in almost a single plane, like on the surface of a table. Voyager 1 just moved away from the surface of the table upwards. It could not visit any other planets along this path.

Voyager 2 reached Saturn in 1981. After evaluation it was found that Voyager 2 can proceed to Uranus which it reached in 1986. Voyager 2 next proceeded to Neptune in 1989 after which it left the planetary plane towards the interstellar space. While Voyager 1 went above the surface of the table, Voyager 2 went below the surface of the table. Voyager 1 entered heliopause in 2012. It has since entered the interstellar space, beyond the confines of our solar system.

We learnt a lot about the outer planets and their moons due to the data gathered by the instruments aboard these space probes. Several cameras and spectrographs captured the details and sent them back to Earth. NASA’s deep space network receives such signals from distant space probes. The radio antennas with dishes 200 feet across in California, Australia and Spain catch these feeble signals. Voyager 1 is about 1.3 billion miles away and the radio signal takes about 19 hours to reach us.

The nuclear fuel in the Voyagers is expected to last till 2025. What will happen after it runs out of fuel ? They may loiter around in the interstellar space for some time until captured by another star. Certainly they will not be able to send us any signals back. The golden record, which contains a sample of human music and pictures may be found by some other civilization. The probes will not be able to leave our galaxy as they would need to attain speeds of about a million miles per hour to do so.

The less sophisticated but reliable technology is still working like a charm. Compared to the more complex cell phones and computers we have to throw away every few years.

Below is a picture of the trajectories of the two space probes, courtesy NASA.

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compiled by Arlene & David Kaplan

Ross 128 & its planet - NYT

Ross 128 & its planet – NYT

A Nearby Earth-Size Planet May Have Conditions for Life
There’s a new place to look for life in the universe. Astronomers announced on Wednesday the discovery of an Earth-size planet around a small red star in our corner of the galaxy. The planet could hold liquid water and conditions favorable for life…more

Long erupting 'Zombie' star -BBC - BBC

Long erupting ‘Zombie’ star -BBC

‘Zombie’ star survived going supernova
It’s the astronomical equivalent of a horror film adversary: a star that just wouldn’t stay dead.
When most stars go supernova, they die in a single blast, but astronomers have found a star that survived not one, but five separate explosions…more

Babylonian Tablet - NYT

Babylonian Tablet – NYT

Signs of Modern Astronomy Seen in Ancient Babylon
For people living in the ancient city of Babylon, Marduk was their patron god, and thus it is not a surprise that Babylonian astronomers took an interest in tracking the comings and goings of the planet Jupiter, which they regarded as a celestial manifestation of Marduk…more

The brightest parts of the UK are getting brighter - BBC

The brightest parts of the UK are getting brighter – BBC

Light pollution: Night being lost in many countries
A study of pictures of Earth by night has revealed that artificial light is growing brighter and more extensive every year. Between 2012 and 2016, the planet’s artificially lit outdoor area grew by more than 2% per year…more

Black hole mergers - BBC

Black hole mergers – BBC

‘Routine’ detection of space ripples
Gravitational waves have been picked up from another black hole merger. It is the fifth time such an event has been validated, and the sixth occasion overall that ripples in space-time have been detected from far-off phenomena. The LIGO-VIRGO collaboration, whose laser labs sense the waves, issued the news via a simple press release…more

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